The present invention relates to compounds to confer release properties to cellulose supports.
Specifically, the invention relates to the treatment of cellulose supports, such as paper, cardboard, etc., with particular fluorinated derivatives such as to confer release properties. With xe2x80x9creleasexe2x80x9d the capability of the treated surface to allow an easy manual release of adhesives, such as for example labels, is meant.
It is known in the prior art that labels are commercialized on paper supports treated with high amounts of silicone polymers to confer release properties which imply an easy manual release of the labels from the paper supports. In EP 608,780 a fluorosilicone composition is described which applied to the surface of various substrata, such as for example, paper, synthetic textiles, after a suitable thermal crosslinking treatment at high temperature, causes the formation of a film which confers to the paper release properties towards adhesive substances. The drawback of the use of the above mentioned fluorosilicone compositions resides in that they require an application process wherein the treating composition is applied to the substratum dissolved in an organic solvent. The commonly used organic solvents are aromatic, aliphatic and halogenated hydrocarbons, which are generally flammable and/or toxic liquids. These treatments cannot therefore be carried out on line, (directly in paper mill), but they require specific plants. A further drawback consists in that after the solvent evaporation, a crosslinking phase of the silicone polymer at high temperature, in the range 100-150xc2x0 C., is necessary.
When aqueous silicone dispersions are used, the conferred release properties are worsened with respect to the case when the silicone dispersions are dissolved in an organic solvent.
The need was felt to have available products capable to confer improved release properties, applicable from completely aqueous formulations or aqueous formulations containing reduced amounts of co-solvent, with the maximum value of 10% with respect to water, without requiring a crosslinking phase at high temperature.
The Applicant has unexpectedly and surprisingly found specific compounds able to overcome the above mentioned drawbacks of the prior art, improving the release properties conferred to cellulose supports when said compounds are applied from aqueous or prevailingly aqueous formulations.
An object of the present invention are therefore fluorinated compounds and their use to confer release properties to cellulose substrata, said fluorinated compounds being selected from the following structures:
(A) [Rfxe2x80x94CFYxe2x80x94Lxe2x80x94O]mP(O) (Oxe2x88x92Z+)3xe2x88x92m 
(B) (Oxe2x88x92Z+)2P (O) [Oxe2x80x94Lxe2x80x94YFCxe2x80x94Oxe2x80x94Rfxe2x80x94CFYxe2x80x94Lxe2x80x94Oxe2x80x94P(O)(Oxe2x88x92Z+)]mxe2x80x2xe2x80x94xe2x80x94[Oxe2x80x94Lxe2x80x94YFCxe2x80x94Oxe2x80x94Rfxe2x80x94CFYxe2x80x94Lxe2x80x94O]P(O) (Oxe2x88x92Z+)2 
(C) Fluorinated (meth)acrylic copolymers
(D) [Rtxe2x80x94CF2xe2x80x94SO2N (U1) (U2)xe2x80x94O]gxe2x80x94P(O) (OZ)3xe2x88x92g 
in the compounds of structure (A) and (B) the following definitions mean:
mxe2x80x2 is an integer from 0 to 20, preferably from 0 to 4;
L is an organic group selected from xe2x80x94CH2xe2x80x94(OCH2CH2)nxe2x80x94, xe2x80x94COxe2x80x94NRxe2x80x2xe2x80x94(CH2)qxe2x80x94, with Rxe2x80x2xe2x95x90H or C1-C4 alkyl group;
n=0-8, preferably 1-3, q=1-8, preferably 1-3;
Zxe2x95x90H, alkane metal or a NR4 group with Rxe2x95x90H or C1-C4 alkyl group;
Yxe2x95x90F, CF3;
m=1,2,3, preferably 1,2;
Rf has a number average molecular weight in the range 350-8,000, preferably 500-3,000 and it comprises repeating units having at least one of the following structures, statistically placed along the chain:
(CFXO), (CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O), (CR4R5CF2CF2O) , (CF CF3) CF2O), (CF2CF(CF3)O),
wherein
X=F, CF3;
R4 and R5, equal to or different from each other, are selected from H, Cl, or perfluoroalkyl from 1 to 4 carbon atoms;
in the structure (D) the following definitions mean:
Rt is a linear or branched when possible perfluorocarbon radical having from 1 to 20 carbon atoms, preferably from 6 to 10 carbon atoms;
U1, U2 equal to or different from each other, are selected from linear or branched C1-C8 alkyl groups, (CH2CH20)Q ethylenoxide groups, wherein Q is in the range 1-20, preferably 1-4;
g is an integer in the range 1-3.
Mixtures of two or more of the compounds (A), (B), (C) and (D) can also be used.
In particular Rf in the structures (A) and (B) can have one of the following structures:
1) xe2x80x94(CF2O)axe2x80x2xe2x80x94(CF2CF2O)bxe2x80x2xe2x80x94
xe2x80x83with axe2x80x2/bxe2x80x2 in the range 0.5-2, extremes included, axe2x80x2 and bxe2x80x2 being integers such as to give the above mentioned molecular weight;
2) xe2x80x94(C3F6O)rxe2x80x94(C2F4O)bxe2x80x94(CFXO)txe2x80x94
xe2x80x83with r/b=0.5-2.0; (r+b)/t is in the range 10-30, b, r and t being integers such as to give the above mentioned molecular weight, X has the above mentioned meaning;
3) xe2x80x94(C3F6O)rxe2x80x2xe2x80x94(CFXO)txe2x80x2xe2x80x94
xe2x80x83txe2x80x2 can be 0;
xe2x80x83when txe2x80x2 is different from 0 then rxe2x80x2/txe2x80x2=10-30, rxe2x80x2 and txe2x80x2 being integers such as to give the above mentioned molecular weight; X has the above indicated meaning;
4) xe2x80x94(OCF2CF(CF3))zxe2x80x94OCF2(Rxe2x80x2f)yxe2x80x94CF2Oxe2x80x94(CF(CF3)CF2O)zxe2x80x94
xe2x80x83wherein z is an integer such that the molecular weight is the above mentioned one;
xe2x80x83y is an integer between 0 and 1 and Rxe2x80x2f is a fluoroalkylene group having for example 1-4 carbon atoms;
5) xe2x80x94(OCF2CF2CR4R5)qxe2x80x94OCF2(Rxe2x80x2f)yxe2x80x94CF2Oxe2x80x94 (CR4R5CF2CF2O)sxe2x80x94
xe2x80x83wherein:
xe2x80x83q and s are integers such that the molecular weight is the above mentioned one;
xe2x80x83R4, R5, Rxe2x80x2f, y have the above mentioned meaning;
6) xe2x80x94(C3F6O)rxe2x80x2xe2x80x3(CFXO)txe2x80x2xe2x80x3xe2x80x94OCF2(Rxe2x80x2f)yxe2x80x94CF2O(CF(CF3)CF2O)rxe2x80x2xe2x80x3(CFXO)txe2x80x2xe2x80x3xe2x80x94
xe2x80x83wherein
xe2x80x83rxe2x80x2xe2x80x3/txe2x80x2xe2x80x3=10-30,
xe2x80x83rxe2x80x2xe2x80x3 and txe2x80x2xe2x80x3 being integers such as to give the above mentioned molecular weight;
xe2x80x83Rxe2x80x2f and y having the above mentioned meaning.
In the above indicated formulas:
xe2x80x94(C3F6O)xe2x80x94 can represent units of formula xe2x80x94(CF(CF3)CF2O)xe2x80x94 and/or xe2x80x94(CF2xe2x80x94CF (CF3)O)xe2x80x94
In the structure (A) wherein Rf is monofunctional, the other end group is of the Txe2x80x94Oxe2x80x94 type, wherein T is a (per)-fluoroalkyl group selected from: xe2x80x94CF3, xe2x80x94C2F5, xe2x80x94C3F7, xe2x80x94CF2Cl, xe2x80x94C2F4Cl, xe2x80x94C3F6Cl; optionally one or two F atoms, preferably one, can be replaced by H.
Among the compounds of structure (A) the following compounds are already known for other applications:
m=2, Rf of structure 3) wherein txe2x80x2=0, rxe2x80x2=1-8, Z=H, alkaline metals, optionally substituted ammonium ion, T=xe2x80x94C2F5, xe2x80x94C3F7;
m=1 and Rf having structure 1)-6), T=perfluorinated group optionally containing one chlorine atom.
The mentioned fluoropolyethers (A) and (B) are obtainable by the well known processes in the prior art, see for example the following patents herein incorporated by reference: U.S. Pat. Nos. 3,665,041, 2,242,218, 3,715,378, and EP 239123. The functionalized fluoropolyethers having hydroxyl termination are for example obtained according to EP 148482, U.S. Pat. No. 3,810,874.
The preparation of the monofunctional (per)fluoropolyether phosphates of structure (A) can be carried out by reacting the corresponding hydroxy-terminated (per) fluoroalkylenoxides with POCl3. To obtain the monoester derivative (m=1) it is necessary to use a molar ratio POCl3/hydroxy-terminated compound in the range 2/1-10/1, preferably 6/1-8/1. The reaction is carried out by slowly dropping the hydroxy-terminated compound in POCl3, at a temperature between 50 and 100xc2x0 C., preferably between 70xc2x0 and 80xc2x0 C., removing the HCl vapours in a KOH trap. The POCl3 excess is removed by distillation while the formed adduct is hydrolysed by H2O. The separation of the obtained product takes place by extraction with a suitable organic solvent, such as for example ethyl acetate. The product of structure (A) with m=1 is separated from the organic phase according to known techniques, for example by solvent evaporation.
To obtain the biester derivative (m=2) of formula (A) one proceeds as in the monoester case with the difference that after the POCl3 removal, the reaction adduct is furtherly reacted with an equimolar amount of hydroxy-terminated compound. Subsequently hydrolysis is carried out and one proceeds as above described.
To obtain the triester derivative (m=3) of formula (A) one proceeds as in the monoester case with the difference that after the POCl3 removal, the reaction adduct is furtherly reacted with a bimolar amount of hydroxy-terminated compound. Subsequently hydrolysis is carried out and one proceeds as above described.
The preparation of the bifunctional (per) fluoropolyether phosphates of structure (B) can be carried out by reacting the corresponding di-hydroxy-terminated (per)fluoroalkylenoxides with POCl3. To obtain the derivative with mxe2x80x2=0, it is necessary to use a molar ratio POCl3/di-hydroxy-terminated compound in the range 4/1-20/1, preferably 12/1-16/1. The reaction is carried out by slowly dropping the hydroxy-terminated compound in POCl3, at a temperature between 50 and 100xc2x0 C., preferably between 70xc2x0 and 80xc2x0 C., removing the HCl vapours in a KOH trap. The POCl3 excess is removed by distillation while the formed adduct is hydrolysed by H2O. The separation of the product (B) with mxe2x80x2=0 takes place by extraction with a suitable organic solvent, such as for example ethyl acetate. The product is separated from the organic phase according to known techniques, for example by solvent evaporation.
To obtain the product of structure (B) with mxe2x80x2 greater than 0, one proceeds as in the case mxe2x80x2=0 with the difference that after the POCl3 removal, the reaction adduct is furtherly reacted with variable amounts of the di-hydroxy-terminated compound. Subsequently hydrolysis is carried out and the above described procedure is performed.
The compound (C) used in the present invention is formed by (meth)acrylic monomers comprising perf luoroalkyl groups having C3-C30 chain, linear or branched, or perfluoropolyether groups having chain from 4 to 30 carbon atoms; optionally one or more sulphonamide groups, hydrogenated (meth)acrylic monomers and cation and/or anion (meth)acrylic ionomer monomers.
As examples of these monomers reference is preferably made to the formulas (I), (II), (III) and (IV) reported hereunder, wherein the substituents have the mentioned meanings.
These fluoro(meth)acrylated copolymers are for example described in U.S. Pat. Nos. 2,803,615, 2,839,513, 2,995,542, 3,814,741, 3,356,628, 3,536,749, 4,525,423, 4,529,658, EP 622,653 and EP 870,778 as precursor acrylic monomers.
Said copolymers can be prepared for example by emulsion polymerization, in the presence of an emulsifier, catalyst and chain transfer agent as described for example in U.S. Pat. No. 4,525,423. For example the fluoroacrylated copolymers (C) can be obtained by using the following monomers in the indicated amounts:
a) from 1 to 30% by weight of monomers or monomer mixtures of formula
R1O(R2O)nII[C(O)CH2O]mIICOCHxe2x95x90CH2xe2x80x83xe2x80x83(II)
xe2x80x83wherein
xe2x80x83R1 is a C1-C20 alkyl, cycloalkyl, haloalkyl, halocycloalkyl group, (halo=Cl, Br);
xe2x80x83R2 is a C1-C6 alkylene or haloalkylene group, each group R2 can be equal to or different from other R2 groups, at least one R1 or R2 group contains one halogen atom, nII is an integer from zero to 10, with the proviso that when n is zero R1 is a C1-C16 haloalkyl or halocycloalkyl group;
xe2x80x83mII is zero or 1;
b) from 60 to 80% of monomers or monomer mixtures of formula
(RfI)pIQOCOCHxe2x95x90CH2xe2x80x83xe2x80x83(I)
xe2x80x83wherein
xe2x80x83RfI is a fluoroalkyl radical having C3-C30, preferably C3-C20, carbon atoms, or it is a perfluoropolyether radical PFPE containing the above mentioned units and having a number of carbon atoms in the range C5-C30;
xe2x80x83pI is 1 or 2;
xe2x80x83Q is a polyvalent binding bridge, C1-C12 divalent from 1 to 12 carbon atoms, or an aromatic radical C3-C12. Q can optionally contain heteroatoms as N, O, S, or carbonylimino, sulphonylimino or carbonyl groups; Q can be unsubstituted or it can contain halogen atoms, hydroxyl groups, C1-C6 alkyl radicals and preferably it does not contain double or triple bonds; preferably Q is xe2x80x94CH2xe2x80x94, xe2x80x94C2H4xe2x80x94, xe2x80x94SO2N(R5)C2H4xe2x80x94, xe2x80x94SO2N(R5)CH2CH(CH3)xe2x80x94, xe2x80x94C2H4SO2N(R5)xe2x80x94C4H8xe2x80x94, R5 is H or a C1-C4 alkyl group;
c) from 0 to 15%, preferably from 1 to 15% of monomers or monomer mixtures of formula 
xe2x80x83wherein R3 is H or methyl;
d) from 1 to 6% of cation and/or anion monomers, or mixtures thereof, of formula
CH2xe2x95x90C (R4)ZIVYIVXxe2x80x83xe2x80x83(IV)
wherein R4 is H or methyl,
xe2x80x83the group ZIV has a carbonyl or aromatic group or one oxygen or sulphur atom directly bound to the vinylidene radical of the monomer; the group ZIV can be preferably selected from the following:
xe2x80x94COOCH2CH(OH)CH2xe2x80x94, xe2x80x94COO(CH2)kIVxe2x80x94, xe2x80x94CONH(CH2)kIV,
xe2x80x83wherein kIV is an integer from 2 to 6;
xe2x80x83YIV can be of the cation type YIV+ and it is preferably selected from: (a) pyridinium ion, (b) N+(R6)3 ion wherein each R6 is independently H or a C1-C4 alkyl group, or two of any R6 combine to form a C4-C5 alkylene group, or two of any R6 are xe2x80x94(CH2)2xe2x80x94 and combine with one oxygen atom to give the structure xe2x80x94(CH2)2xe2x80x94Oxe2x80x94(CH2)2xe2x80x94, (c) phosphonium ions and (d) sulphonium ions; preferably YIV+ is N+(R6)3 wherein
xe2x80x83R6 is as above defined;
xe2x80x83X is of anion type Xxe2x88x92, when YIV is of cation type and it is preferably an halide (Cl, Br, I) or an alkyl sulphate;
YIV can be of anion type YIVxe2x88x92 and it is preferably selected from carboxyl and sulphonic groups;
xe2x80x83X is of cation type X+, when YIV is of anion type and it is preferably H, alkaline metal, ammonium, or cations deriving from primary and secondary amines;
e) from 0 to 20% of monomers containing at least a double bond, such as for example maleic anhydride, acrylonitrile, vinyl acetate, vinyl chloride, vinyl fluoride, vinyliden fluoride, vinyliden cyanide, vinyl chloroacetate, vinyl silicone, ethylene, styrene, alkyl styrenes, halogenated styrenes, methacrylonitrile, N-vinyl carbazole, vinyl pyridine, vinyl alkyl ethers, vinyl alkyl ketones, isoprene, butadiene, chloroprene, fluoroprene, and mixtures thereof.
The preferred monomers of group a) are the esters alkyl, cycloalkyl, haloalkyl, halocycloalkyl (halo=Cl, Br) from 1 to 20 carbon atoms of the acrylic or methacrylic acid.
The preferred monomers of group b) are those containing C4-C12 perfluoroalkyl chains, still more preferably containing the sulphonamide group, such as for example C8F17SO2N(CH3)CH2CH2OCOCHxe2x95x90CH2; when RfI is based on PFPE, Txe2x80x2O(C3F6O)rxe2x80x2(CF2O)txe2x80x2CF2CH2OCH2CH2OCOC(CH3)xe2x95x90CH2 can be mentioned, wherein
Txe2x80x2=C1-C3 perfluoroalkyl, optionally one or more F atoms of Txe2x80x2, generally one F atom, are substituted by H and/or Cl; rxe2x80x2 and txe2x80x2 as above defined.
The monomers usable in group b) can also have the structures corresponding to the general formula:
Txe2x80x2Oxe2x80x94(CF2CF2O)bxe2x80x2(CF2O)axe2x80x2xe2x80x94CF2xe2x80x94Aqxe2x80x2xe2x80x3xe2x80x94T0
wherein Txe2x80x2, axe2x80x2 and bxe2x80x2 have the above defined meaning; qxe2x80x2xe2x80x3 is an integer from 0 to 1, A is a bivalent radical, preferably of linear aliphatic type (CH2)mxe2x80x20 wherein mxe2x80x20 is an integer from 1 to 20, or (alkylen)cycloaliphatic, (alkylen)-aromatic type.
The bivalent radical A can optionally contain heteroatoms in the ring or in the alkylene chain, or it can be both a linear and branched polyalkylenoxy chain, in particular containing repeating units of the CH2CH2O, CH2CH(CH3)O, (CH2)3O, (CH2)4O type. A can also contain groups of amide, ester, ether, COO, sulphur, imine type; the number of carbon atoms of the cycloaliphatic compounds being from 3 to 20, for the aromatic ones from 5 to 20; the group A can also be a combination of the indicated types; the bond group of A with the perfluoromethylene group of the fluorinated chain can be for example: xe2x80x94Cxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94CONRxe2x80x94 (R is H, alkyl, cycloaliphatic or aromatic groups with less than 15 carbon atoms), xe2x80x94CO2xe2x80x94, xe2x80x94COSxe2x80x94, xe2x80x94COxe2x80x94, one heteroatom, or the triazinic, or the heterocyclic aromatic groups having 5 or 6 atoms containing 2 or more heteroatoms equal to or different from each other; T0 is xe2x80x94COOCHxe2x95x90CH2, xe2x80x94COOCH2CHxe2x95x90CH2.
The compound (C) used in the present invention is available on the market under the form of aqueous dispersions of fluoroacrylates, for example as Scotchgard(copyright), Scotchban(copyright) by 3M.
The compounds of the invention are used in aqueous formulations, optionally in the presence of a co-solvent having a concentration lower than 10% by weight. The co-solvent is selected from aliphatic alcohols having from 1 to 6 carbon atoms; aliphatic glycols having from 2 to 8 carbon atoms, optionally having an esterified hydroxyl; ketones or esters having from 3 to 10 carbon atoms.
When the compounds of the invention are used alone in the application phase, the treating aqueous solution has a concentration in the range 0.1-30% by weight, preferably 1-10% by weight, and it is applied by the techniques mentioned below.
To obtain good release properties the amount of the applied compound for treated surface unit is in the range 0.01-10 g/m2, preferably 0.1-2 g/m2.
The preferred compounds of the invention are those having structure (B).
The described products having structure (A), (B), (C) and (D), preferably the compound of structure (B), are also usable as release additives of formulations for various applications in the manufacture of papers, for example special papers.
The compounds of the invention are for example usable as release additives of aqueous silicone emulsions in coating applications of papers in confectionery, where the release property of the paper with respect to the food is important or in the label field where the release property of the paper with respect to the glue is important.
Another example of application of the products of the invention relates to their use as release additives of acrylic or silicone thermoweldable aqueous dispersions. The paper at present used in packaging is often coupled with a polyethylene film which forms a barrier towards the absorption of oils and greases and at the same time it allows the paper thermoweldability to obtain bags of different size and shape. By the products of the invention, silicone or acrylic aqueous dispersions can directly be used in paper mill to obtain thermoweldable coatings which allow the paper recycle. In fact the invention products allow, when additived with the above mentioned thermoweldable coatings to avoid the tackiness thereof at room temperature while allowing to maintain the weldability features unchanged at a temperature in the range 100-170xc2x0 C.
The compounds of the invention, when used as release additives, are used in a ratio by weight in the range 1:1-1:50, preferably 1:3-1:30, with respect to the hydrogenated and/or silicone and/or acrylic polymer.
The compositions containing the additives or the compounds of the invention as such show release properties and give coatings having stable release properties with respect to tacky substances, for example pressure-sensitive adhesives, for example of silicone or acrylic type.
The additived formulation can be applied by coating, dipping or spraying starting from aqueous solutions having a concentration in the range 1%-50% by weight, preferably 10-30% by weight. The amount of the additive applied for treated surface unit is the same as that utilized when compounds as such are used.